System, method, and apparatus for a radially-movable line termination system for a riser string on a drilling rig

ABSTRACT

A line termination assembly for a riser string has a ring adapter mounted to a slip joint and a ring body mounted on top of the ring adapter. The ring adapter radially aligns with the ring body, which forms an inner diameter for receiving the slip joint. The ring body also has a discontinuity for radial access to the inner diameter, such that the ring body is circumferentially discontinuous. The discontinuity defines a chord dimension that exceeds the outer diameter of the slip joint, such that the slip joint may move radially through the discontinuity and into the inner diameter during assembly and disassembly of the system. Fluid bearings and tension rings are mounted to the slip joint and are axially spaced apart from the ring adapter and the ring body.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates in general to terminating choke, kill, andauxiliary lines for riser strings on an offshore drilling rig and, inparticular, to an improved system, method, and apparatus for a linetermination system that is radially-movable relative to the riserstring.

2. Description of the Related Art

Offshore drilling rigs must compensate for many environmental hazardsincluding tidal conditions, ocean swells, and weather conditions such aswind and severe weather. The forces generated by these hazards causesignificant motion of the rig that must be compensated to maintain thecontinuity of the riser string that extends down from the rig and isfixed to the ocean floor. A slip joint is typically used near an upperend of the riser string to compensate for vertical motion of the rig.The slip joint compensates for motion with inner and outer barrels thatmove axially relative to each other. The various choke, kill, andauxiliary lines associated with riser strings also must be configured tocompensate for motion. These lines are typically terminated adjacent theslip joint with a device such as a Karrot Top or KT ring assembly.

A conventional KT ring assembly 11 is shown in FIG. 1 and comprises aring adapter 13 that is mounted to the outer barrel 15 of the slip joint17. The ring adapter 13 lands on a shoulder 19 inside a large, solidring body 21, which completely circumscribes the ring adapter 13 andslip joint 17. The ring body 21 includes numerous terminal blocks 23 forterminating the choke, kill, and auxiliary lines. The ring body 21 alsotypically incorporates a fluid bearing 25 and a tension ring 27 forsupporting the overall assembly.

Although conventional KT rings provide numerous advantages they alsohave a few limitations. For example, because the ring body is solid, theentire riser string must be run through the KT ring assembly duringconstruction of the riser string. The large size of the ring body makesit somewhat cumbersome to manipulate, and it consumes significant spacebetween the floors of drilling rig. In addition, the ring body mustfirst be secured to the bottom of the diverter housing. Thus, althoughconventional KT rings are workable, an improved design would bedesirable.

SUMMARY OF THE INVENTION

One embodiment of a system, method, and apparatus for a line terminationassembly comprises a ring adapter that is mounted to a slip joint and aring body mounted to the ring adapter. The ring adapter has an uppersurface with a recess formed therein, and the ring body has a lowersurface with a protuberance extending therefrom seated in the recess onthe ring adapter for radial alignment therebetween. The ring body formsan inner diameter that is located radially inward from the protuberance.Lock pins secure the ring adapter to the ring body, and a key pin on thering body rotationally aligns the ring body with the ring adapter via akey receptacle on the ring adapter.

The ring body also has a discontinuity such that the ring body iscircumferentially discontinuous with respect to the slip joint. Thediscontinuity defines a chord dimension that exceeds the outer diameterof the slip joint, such that the slip joint may move in a radialdirection, relatively speaking, through the discontinuity and into theinner diameter during assembly and disassembly of the riser string.Terminal blocks are mounted to the ring body for terminating the choke,kill, and auxiliary lines. The ring body may be removed from the slipjoint in the radial direction, positioned on a mandrel, andindependently tested with the termination lines separately from the ringadapter. The fluid bearings and tension rings of the system are directlymounted to the slip joint and are axially spaced apart from the ringadapter and the ring body.

The foregoing and other objects and advantages of the present inventionwill be apparent to those skilled in the art, in view of the followingdetailed description of the present invention, taken in conjunction withthe appended claims and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the features and advantages of theinvention, as well as others which will become apparent are attained andcan be understood in more detail, more particular description of theinvention briefly summarized above may be had by reference to theembodiment thereof which is illustrated in the appended drawings, whichdrawings form a part of this specification. It is to be noted, however,that the drawings illustrate only an embodiment of the invention andtherefore are not to be considered limiting of its scope as theinvention may admit to other equally effective embodiments.

FIG. 1 is a sectional side view of a conventional KT ring assembly;

FIG. 2 is an isometric view of one embodiment of a line terminationassembly constructed in accordance with the present invention;

FIG. 3 is a top view of the line termination assembly of FIG. 2 showninstalled on a slip joint and is constructed in accordance with thepresent invention;

FIG. 4 is an enlarged, half-sectional side view of the line terminationassembly and slip joint of FIG. 3, taken along the line 4-4 of FIG. 3,and is constructed in accordance with the present invention; and

FIG. 5 is a high level flow diagram of one embodiment of a methodconstructed in accordance with the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIGS. 2-5, one embodiment of a system, method, andapparatus constructed in accordance with the present invention is shown.The present invention comprises a line termination system 21 (FIGS. 3and 4) for a riser string and is well suited for use with a slip joint23 having an axis 25 and an outer barrel 27 with an outer diameter 29. Aring adapter 31 is mounted to the outer barrel 27 of the slip joint 23.The ring adapter 31 has an upper surface 33 with a recess 35 formedtherein and, in one embodiment, the ring adapter 31 is circumferentiallycontinuous with respect to the slip joint 23.

The line termination system 21 also includes a ring body 41 (FIGS. 2-4)that is mounted to the ring adapter 31. The ring body 41 has a lowersurface 43 (FIG. 4) with a protuberance 45 extending therefrom. Theprotuberance 45 seats in the recess 33 on the ring adapter 31 to provideradial alignment between the ring adapter 31 and ring body 41. In oneembodiment, the protuberance 45 on the ring body 41 is a semi-circularrim, and the recess 33 on the ring adapter 31 is a circular trough. Asshown in FIG. 3, lock pins 42 are used to secure the ring adapter 31 tothe ring body 41. A key pin 50 on the ring body 41 is used torotationally align the ring body 41 with a key receptacle 52 on the ringadapter 31.

A discontinuity 47 is formed in the ring body 41 such that the ring body41 is circumferentially discontinuous with respect to the slip joint 23.The ring body 41 has an inner diameter 49 that is located radiallyinward from the protuberance 45. The discontinuity 47 defines a chorddimension 51 that exceeds the outer diameter 29 of the outer barrel 27of the slip joint 23. This configuration allows the ring body 41 to moveradially relative to the slip joint 23. The slip joint 23 passes throughthe discontinuity 47 in a radial direction and into the inner diameter49 during assembly and disassembly of the riser string. In addition, thering body 41 may be removed from the slip joint 23 in the radialdirection, positioned on a mandrel, and independently tested with thechoke, kill, and auxiliary lines separately from the ring adapter 31.

The ring body 41 also includes a number of terminal blocks 44 mounted tothe ring body 41 for terminating choke, kill, and auxiliary lines 46.Significantly, any fluid bearings and tension rings required by theriser string are mounted directly to the slip joint 23 and are axiallyspaced apart from the ring adapter 31 and the ring body 41. The tensionring has riser tensioner lines secured thereto.

The present invention also comprises a method of forming lineterminations for a riser string. As shown in FIG. 5, one embodiment ofthe method begins as indicated in step 101, and comprises providing aslip joint with an axis (step 103); mounting a ring adapter to the slipjoint (step 105); providing a ring body with terminal blocks and adiscontinuity such that the ring body is circumferentially discontinuouswith respect to the slip joint (step 107); mounting the ring body to thering adapter by relative movement of the slip joint through thediscontinuity (step 109); terminating termination lines associated withthe riser string on the terminal blocks on the ring body (step 111);before ending as indicated at step 113.

The method may further comprise defining a chord dimension with thediscontinuity that exceeds an outer diameter of the slip joint, andradially moving the ring body such that the slip joint passes throughthe discontinuity during assembly and disassembly of the riser string.The method also may comprise landing the ring body on top of the ringadapter and radially aligning the ring body with the ring adapter.

In addition, the method may further comprise removing the ring body fromthe slip joint in a radial direction, positioning the ring body on amandrel, and independently testing the ring body and termination linesseparately from the ring adapter; and/or mounting a fluid bearing and atension ring to the slip joint axially spaced apart from the ringadapter and the ring body, and securing tensioner lines to the tensionring; and/or securing the ring adapter to the ring body with a pluralityof lock pins, and rotationally aligning the ring body to the ringadapter with a key pin and a key receptacle.

The present invention has several advantages, including the ability tobe laterally or radially removed from the slip joint so that the entireriser string does not have to be run through the KT ring assembly forany construction on the riser string. The ring body is much smaller thanconventional designs, is much easier to manipulate, and consumessignificantly less space than its predecessors. In addition, thetermination lines can remain secured to the ring body even after it isremoved from the slip joint. This feature allows the ring body to betested independently from the remaining components of the assembly.Moreover, no termination joint is required beneath the slip joint.

While the invention has been shown or described in only some of itsforms, it should be apparent to those skilled in the art that it is notso limited, but is susceptible to various changes without departing fromthe scope of the invention.

1. A line termination system for a riser string, comprising: a slipjoint having an axis and an outer diameter; a ring adapter mounted tothe slip joint and having an adapter feature formed therein; a ring bodymounted to the ring adapter and having a body feature for engaging theadapter feature on the ring adapter for radial alignment therebetween,and a discontinuity formed in the ring body such that the ring body iscircumferentially discontinuous with respect to the slip joint, whereinthe discontinuity defines a dimension that exceeds the outer diameter ofthe slip joint, such that the ring body moves radially with respect tothe slip joint such that the slip joint passes through the discontinuityduring assembly and disassembly of the riser string; and a plurality ofterminal blocks mounted to the ring body for terminating terminationlines associated with the riser, wherein the plurality of terminalblocks are in fluid communication with the termination lines associatedwith the riser string via the ring adapter string.
 2. A line terminationsystem according to claim 1, wherein the ring adapter iscircumferentially continuous with respect to the slip joint and the ringbody, the body feature on the ring body is a semi-circular rim, and theadapter feature on the ring adapter is a circular trough.
 3. A linetermination system according to claim 1, wherein the ring body isremoved from the slip joint in the radial direction, positioned on amandrel, and independently tested with the termination lines separatelyfrom the ring adapter.
 4. A line termination system according to claim1, further comprising a fluid bearing and a tension ring, each directlymounted to the slip joint and axially spaced apart from the ring adapterand the ring body, the tension ring having riser tensioner lines securedthereto.
 5. A line termination system according to claim 1, furthercomprising a plurality of lock pins for securing the ring adapter to thering body, and a key pin on the ring body for rotationally aligning thering body with a key receptacle on the ring adapter.
 6. A linetermination system for a riser string, comprising: a ring adaptersecurable to a slip joint of a riser string and in fluid communicationwith at least one fluid line of the riser string; a ring body adapted toextend circumferentially around a portion of the ring adapter and besecurable to the ring adapter, the ring body having a discontinuityformed in the ring body such that the ring body is circumferentiallydiscontinuous with respect to the ring adapter; the discontinuitydefining a chord dimension that exceeds the outer diameter of a portionof the riser string, such that the portion of the riser string passesthough the discontinuity as the ring body is secured to the ring adapterand released from the ring adapter during assembly and disassembly ofthe riser string; and a plurality of terminal blocks mounted to the ringbody and in fluid communication with the ring adapter for terminatingthe at least one fluid line of the riser string.
 7. A line terminationsystem according to claim 6, wherein the ring adapter comprises a recesson an upper surface and the ring body comprises a protuberance on alower surface, the protuberance on the ring body being a semi-circularrim and the recess on the ring adapter being a circular trough.
 8. Aline termination system according to claim 6, wherein the ring body isdisposed in a radial direction relative to the portion of the riserstring.
 9. A line termination system according to claim 6, furthercomprising the slip joint, a fluid bearing, and a tension ring, thefluid bearing and tension ring being directly mounted to the slip jointand axially spaced apart from the ring adapter and the ring body, thetension ring having riser tensioner lines secured thereto.
 10. A linetermination system according to claim 6, further comprising a pluralityof lock pins for securing the ring adapter to the ring body, and a keypin on the ring body for rotationally aligning the ring body with a keyreceptacle on the ring adapter.
 11. A line termination system accordingto claim 6, wherein the portion of the riser string is the ring adapter.12. A method of forming line terminations for a riser string,comprising: (a) providing a slip joint with an axis; (b) mounting a ringadapter to the slip joint; (c) providing a ring body with terminalblocks and a discontinuity such that the ring body is circumferentiallydiscontinuous with respect to the slip joint, wherein providing a ringbody with a discontinuity comprises defining the discontinuity with achord dimension that exceeds an outer diameter of the slip joint; (d)mounting the ring body to the ring adapter by relative movement of theslip joint through the discontinuity, wherein mounting the ring body tothe ring adapter comprises radially moving the ring body such that theslip joint passes through the discontinuity during assembly anddisassembly of the riser wherein the plurality of terminal blocks are influid communication with the termination lines associated with the riserstring via the ring adapter string; and (e) terminating terminationlines associated with the riser string on the terminal blocks on thering body.
 13. A method according to claim 12, wherein step (d)comprises landing the ring body on top of the ring adapter and radiallyaligning the ring body with the ring adapter.
 14. A method according toclaim 12, further comprising removing the ring body from the slip jointin a radial direction, positioning the ring body on a mandrel, andindependently testing the ring body and termination lines separatelyfrom the ring adapter.
 15. A method according to claim 12, furthercomprising mounting a fluid bearing and a tension ring directly to theslip joint axially spaced apart from the ring adapter and the ring body,and securing tensioner lines to the tension ring.
 16. A method accordingto claim 12, further comprising securing the ring adapter to the ringbody with a plurality of lock pins, and rotationally aligning the ringbody to the ring adapter with a key pin and a key receptacle.